The drivetrain or powertrain refers to the group of components that generate power and deliver it to the road surface, which can include for example the engine, transmission, driveshafts, differentials, and the final drive (wheels, tracks, etc.). Due to the transmission or other components, the drivetrain limits available rim-pull (force available at the road surface) for a particular ground speed. Direct drive or torque converter machines have rim-pull limitations based upon the engine torque curve, efficiency losses, and other limitations due to having fixed discrete ratios between the engine and the wheels. An infinitely variable transmission can allow the engine to operate constantly at its peak power as it can operate effectively at an infinite number of gear ratios. This can enable expansion of the rim-pull performance beyond what is available in a conventional powertrain, although limits will still exist. A series electric powertrain is an example of a drivetrain that is both infinitely variable and has control of the rim-pull within the operating limits. This will be the exemplary drivetrain used for the rest of this application.
Work vehicles can operate in various environments, have various duties and have different operators with different preferences. For example, a loader may make countless maneuvers of getting a load of material from a pile, backing up from the pile, approaching a hauler, stopping and dumping the load in the hauler, backing up from the hauler, approaching the material pile and getting another load. This repetitive process requires constant forward, stop, reverse, stop movements which can cause excessive wear on service brakes of the vehicle if they are utilized and will affect how much energy is returned to the engine drive-shaft during deceleration thereby affecting total fuel consumption. Additionally, over the course of a day, operator fatigue can significantly affect overall productivity.
It would be desirable to have operator selectable characteristics for the powertrain to meet the operator preferences and/or to customize the characteristics to the job parameters. The comfort level for each operator may be determined by the particular type of powertrain they frequently operate on other machines, for example hydrostatic transmissions, torque converter transmissions, or direct drive transmissions. It would also be desirable to have the transmission help in the braking process to reduce the amount of braking the operator needs to do with the service brakes, thus extending the life of the service brakes and improving fuel economy. Allowing the operator to select operating modes that result in more transmission braking provides more kinetic energy to power other vehicle loads and reduce/eliminate engine fueling. By enabling operator selectable feel, the operator can determine what transmission characteristic is most comfortable to them and the most appropriate for the job.